The Briton, who looked after ECR's Spencer Pigot in the No. 21 Chevy during the recent Manufacturers test at Road America, brings considerable experience, which includes a Verizon IndyCar Series championship and Indy 500 win with Dario Franchitti, to the Bowtie program.

McDonald replaces Justin Taylor, who left to rejoin Joest Racing as a race engineer on the Mazda Team Joest IMSA DPi program.

"As soon as I spoke to them, I was super excited and felt it would be a great fit," McDonald told RACER. "I have admired them from afar, and it's a super outfit to join."

McDonald's move to ECR creates an Andretti Green Racing reunion with team manager Tim Broyles and ECR engineering veteran Matt Barnes, who oversees the No. 20 Chevy piloted by team owner Ed Carpenter. Better known today as Andretti Autosport, the trio played important roles during the team's rise in the 2000s.

"I enjoyed working with Tim and Matt before, and the moment it became possible to work with them again, it was an easy decision," said McDonald, whose position within ECR is presently being defined.

"We're still figuring out how I'm going to work with the team, and I enjoyed the test with Spencer. It's clear he's a huge talent."